The story of the conquest of a realm of fable by a campaign of enlightenment is always a tale of interest. The opening of a new vista directs one's gaze outward over unexplored areas. It may be, as our seventeenth-century chronicler tells us, that "we are all Indians and Salvages in what we have not accustomed our senses," and that, "what was Conjuring in the last age is Mathematiques in this"; but our more extensive acquaintance with the course of discovery and the demonstration of truth has given us a more logical sense of the probable and the improbable; and the evolution by which conjuring becomes mathematics is more intimately understood. The recent establishment of hypnotism in its scientific aspects furnishes the proper perspective for the comprehension of its antecedents; it gives confidence that its future development will incorporate the spirit of present research, as it will avoid the aberrations of the past; and it gives to the story of its vicissitudes a timely pertinence as well as a psychological significance. THE NATURAL HISTORY OF ANALOGY I The origin of human endowment lies hidden in an obscure and unrecorded past; the fact of development, of the gradual unfoldment of capacity, stands out conspicuously throughout the historical record of human achievement, and is equally recognizable in the extensive remains of prehistoric humanity. The story of the mental development of man is constructed from travelers' accounts of primitive peoples, from the records of early civilizations, from the sequences of thought and belief that are considered in the history of culture, from the study of the intellectual growth of childhood, from the observation of the less progressive elements of current civilizations. The present essay attempts to portray the status of one form of intellectual process, or of mental attitude, which characterizes undeveloped stages of human thought, and has played an important and variable part in the drama of mental evolution. I propose to present the "Natural History of Analogy,"--meaning thereby the treatment, according to the methods of natural science, of a type of mental action, interesting at once as a psychological process, and again from its practical results as a factor in the anthropological history of the race.